The International Agency for Research on Cancer classified formaldehyde (FA) as a carcinogen based on inhalation caused squamous cell carcinoma in rats and leukemia and nasopharyngeal cancer in humans. Formaldehyde may also be a cause of sinonasal cancer in humans. Infants are particularly susceptible to effects from FA, most likely as a result of the immaturity of their organs and immune system and the time that they spend indoors where FA concentrations are elevated. It was recently reported that exposure while living in housing with levels of 10ppm was correlated with increased risks of lower respiratory tract (32%) and wheezy lower respiratory tract (41%) infections in the first five years of life. Recent studies have shown that exposure to FA results in microRNA changes in the nasal epithelium with subsequent effects on apoptosis signaling. These more serious health effects have been clearly documented at concentrations that are typical in the home and above the NIOSH recommendation and the legal OSHA limit (see below). However, even near the OSHA standard, some people experience burning in the eyes, nose or throat, coughing and even nausea. Formaldehyde is ubiquitous and everyone is exposed by inhalation at some level, both indoors and outdoors. The OSHA, legally enforced, exposure limit for an eight-hour weighted average is 0.75ppm. The short-term exposure limit is 2ppm for a fifteen-minute period. The NIOSH recommended eight-hour exposure limit is 0.016ppm with a short-term recommendation of less than 0.1ppm exposure. Outdoor concentrations are usually in a range from 0.8ppm to 16ppm, but up to 5x higher in heavy traffic. A global indoor concentration range of 3 to 500ppm has been reported with U.S. levels in nonmanufacturing areas such as schools in a range from 3 to 65ppm. The availability of the devices proposed in this document allow for individuals to protect their health by limiting their exposure as it occurs and not simply being tod of exposure at a time when it is too late to rectify the situation. However, there is a second benefit to these new devices. NIH has an established interest in the correlation of exposure to toxic chemicals with measured health effects. Our proposed sensors record cumulative data and allow immediate measurements of exposure so that health researchers can connect the exposure data to health effects. The innovative advantage of our proposed sensors over current time-averaging devices is the real-time record. Researchers will have the data to determine whether measured health effects were the result of long-term exposure exceeding limits or excessive short-term exposure, so that the biological response can be better correlated and understood, leading to safer exposure limits both in the workplace and in homes.